blitzkit/packages/website/src/components/SpacedArmorSceneComponent.tsx

import { isExplosive, resolvePenetrationCoefficient } from "@blitzkit/core";
import { ShellType } from "@blitzkit/protos";
import { useThree } from "@react-three/fiber";
import { useCallback } from "react";
import {
  type Intersection,
  MeshBasicMaterial,
  Object3D,
  Plane,
  Quaternion,
  Raycaster,
  Scene,
  Vector3,
} from "three";
import { degToRad } from "three/src/math/MathUtils.js";
import { defaultEqualizer } from "../config/equalizer";
import { jsxTree } from "../core/blitzkit/jsxTree";
import { discardClippingPlane } from "../core/three/discardClippingPlane";
import { DuelModule, getDuel } from "../hooks/useDuel";
import { hasEquipment } from "../hooks/useEquipment";
import {
  type Shot,
  type ShotLayerBase,
  type ShotLayerNonExternal,
  Tankopedia,
} from "../stores/tankopedia";
import { ArmorType } from "./SpacedArmorScene";
import { SpacedArmorSubExternal } from "./SpacedArmorSubExternal";
import { SpacedArmorSubSpaced } from "./SpacedArmorSubSpaced";

type SpacedArmorSceneComponentProps = {
  node: Object3D;
  thickness: number;
  clip?: Plane;
  scene: Scene;
} & (
  | {
      type: Exclude<ArmorType, ArmorType.External>;
    }
  | {
      type: ArmorType.External;
      variant: ExternalModuleVariant;
    }
);

export type ExternalModuleVariant = "gun" | "track";
export type ArmorUserData = {
  thickness: number;
} & (
  | {
      type: Exclude<ArmorType, ArmorType.External>;
    }
  | {
      type: ArmorType.External;
      variant: ExternalModuleVariant;
    }
);

const PENETRATION_RANDOMIZATION = 0.05;

function resolvePenetrationChance(shoot: (scale: number) => Shot | null) {
  function penetrates(scale: number) {
    const shot = shoot(scale);

    return (shot?.out ?? shot?.in)?.status === "penetration";
  }

  let low = 1 - PENETRATION_RANDOMIZATION;
  let high = 1 + PENETRATION_RANDOMIZATION;

  if (penetrates(low)) return 1;
  if (!penetrates(high)) return 0;

  for (let iteration = 0; iteration < 16; iteration++) {
    const middle = (low + high) / 2;

    if (penetrates(middle)) {
      high = middle;
    } else {
      low = middle;
    }
  }

  return (
    (1 + PENETRATION_RANDOMIZATION - high) / (2 * PENETRATION_RANDOMIZATION)
  );
}

const omitMaterial = new MeshBasicMaterial({
  colorWrite: false,
  depthWrite: true,
});

/**
 * Render orders allocations:
 * - 0  : core omission
 * - 1-2: spaced without depth buffer write but do test to allow additive blending
 * - 3-4: external with depth buffer write in first pass and read in second to simplify geometry
 * - 5  : spaced depth write
 */
export function SpacedArmorSceneComponent({
  node,
  thickness,
  clip,
  ...props
}: SpacedArmorSceneComponentProps) {
  const camera = useThree((state) => state.camera);

  const shoot = useCallback(
    (
      point: Vector3,
      intersections: Intersection[],
      allowRicochet: boolean,
      remainingPenetrationInput?: number,
      penetrationScale = 1,
    ) => {
      const protagonist = getDuel("protagonist", DuelModule.Tank);
      const antagonist = getDuel("antagonist", DuelModule.Tank);

      const { customShell } = Tankopedia.state;
      const shell = customShell ?? getDuel("protagonist", DuelModule.Shell);
      const { equalize } = Tankopedia.state.environment;
      const protagonistEqualizer =
        (equalize ? protagonist.equalizer : undefined) ?? defaultEqualizer;
      const antagonistEqualizer =
        (equalize ? antagonist.equalizer : undefined) ?? defaultEqualizer;
      const cameraNormal = camera.position.clone().sub(point).normalize();
      const shot: Shot = {
        splashRadius:
          shell.type === ShellType.SHELL_TYPE_HE
            ? shell.explosion_radius
            : undefined,
        damage: -1,
        containsGaps: shell.type === ShellType.SHELL_TYPE_HEAT,
        in: {
          surfaceNormal: cameraNormal,
          layers: [],
          status: "blocked",
        },
      };

      const hasCalibratedShells = hasEquipment(
        103,
        antagonist.equipment_preset,
        Tankopedia.state.antagonist.equipment,
      );
      const hasEnhancedArmor = hasEquipment(
        110,
        protagonist.equipment_preset,
        Tankopedia.state.protagonist.equipment,
      );
      const penetration =
        penetrationScale *
        shell.penetration!.near *
        resolvePenetrationCoefficient(
          hasCalibratedShells,
          equalize,
          shell.type,
          antagonistEqualizer,
        );
      const thicknessCoefficient =
        (hasEnhancedArmor ? 1.04 : 1) * protagonistEqualizer.armor;
      const filteredIntersections = intersections.filter(
        (intersection) =>
          "type" in intersection.object.userData &&
          !discardClippingPlane(intersection.object, intersection.point),
      ) as unknown as Intersection<Object3D & { userData: ArmorUserData }>[];
      const encounteredExternalModuleVariants: ExternalModuleVariant[] = [];
      const noDuplicateIntersections: typeof filteredIntersections = [];

      for (const intersection of filteredIntersections) {
        if (intersection.object.userData.type === ArmorType.External) {
          if (
            !encounteredExternalModuleVariants.includes(
              intersection.object.userData.variant,
            )
          ) {
            noDuplicateIntersections.push(intersection);
            encounteredExternalModuleVariants.push(
              intersection.object.userData.variant,
            );
          }
        } else {
          noDuplicateIntersections.push(intersection);

          if (intersection.object.userData.type === ArmorType.Primary) {
            break;
          }
        }
      }

      if (
        !allowRicochet &&
        noDuplicateIntersections.every(
          (intersection) =>
            intersection.object.userData.type !== ArmorType.Primary,
        )
      ) {
        return null;
      }

      let remainingPenetration = remainingPenetrationInput ?? penetration;
      let index = 0;
      for (const intersection of noDuplicateIntersections) {
        const layer = intersection.object.userData;
        const surfaceNormal = intersection
          .normal!.clone()
          .applyQuaternion(
            intersection.object.getWorldQuaternion(new Quaternion()),
          );

        if (shell.type === ShellType.SHELL_TYPE_HEAT && index > 0) {
          const lastLayer = shot.in.layers.at(-1) as ShotLayerBase;
          const distance = lastLayer.point.distanceTo(intersection.point);
          remainingPenetration -= 0.5 * remainingPenetration * distance;
          const blocked = remainingPenetration <= 0;

          shot.in.layers.push({
            type: null,
            distance,
            status: blocked ? "blocked" : "penetration",
          });

          if (blocked) break;
        }

        if (layer.type === ArmorType.External) {
          const thickness = layer.thickness * thicknessCoefficient;
          remainingPenetration -= thickness;
          const blocked =
            remainingPenetration <= 0 || shell.type === ShellType.SHELL_TYPE_HE;

          shot.in.layers.push({
            type: ArmorType.External,
            index,
            thickness,
            point: intersection.point,
            surfaceNormal,
            status:
              shell.type === ShellType.SHELL_TYPE_HE
                ? "blocked"
                : blocked
                  ? "blocked"
                  : "penetration",
            variant: layer.variant,
          });
        } else {
          const thickness = layer.thickness * thicknessCoefficient;
          const ricochet = degToRad(
            isExplosive(shell.type) ? 90 : shell.ricochet!,
          );
          const angle = surfaceNormal.angleTo(cameraNormal);

          const threeCalibersRule =
            shell.caliber > thickness * 3 || index > 0 || !allowRicochet;
          const twoCalibersRule = shell.caliber > thickness * 2;
          const normalization = degToRad(shell.normalization ?? 0);
          const finalNormalization = twoCalibersRule
            ? (1.4 * normalization * shell.caliber) / (2.0 * thickness)
            : normalization;
          const finalThickness =
            thickness / Math.cos(Math.max(0, angle - finalNormalization));

          if (!threeCalibersRule && angle >= ricochet) {
            remainingPenetration *= 0.75;

            shot.in.layers.push({
              type: layer.type,
              index,
              thickness,
              thicknessAngled: finalThickness,
              point: intersection.point,
              surfaceNormal,
              status: "ricochet",
              angle,
            });

            break;
          } else {
            remainingPenetration -= finalThickness;
            const blocked = remainingPenetration <= 0;

            shot.in.layers.push({
              type: layer.type,
              index,
              thickness,
              thicknessAngled: finalThickness,
              point: intersection.point,
              surfaceNormal: intersection.face!.normal,
              status:
                shell.type === ShellType.SHELL_TYPE_HE &&
                layer.type !== ArmorType.Primary
                  ? "blocked"
                  : blocked
                    ? "blocked"
                    : "penetration",
              angle,
            });
          }
        }

        if (
          shell.type !== ShellType.SHELL_TYPE_HE &&
          remainingPenetration <= 0
        ) {
          break;
        }

        index++;
      }

      const lastLayer = shot.in.layers.at(-1) as
        | ShotLayerNonExternal
        | undefined;
      const firstLayer = shot.in.layers[0] as ShotLayerBase | undefined;

      if (!lastLayer || !firstLayer) {
        return null;
      } else {
        if (shell.type === ShellType.SHELL_TYPE_HE) {
          const totalSpacedArmorThickness = shot.in.layers.reduce(
            (acc, layer) => {
              if (layer.type === null || layer.type === ArmorType.Primary) {
                return acc;
              }

              if (layer.type === ArmorType.External) {
                return acc + layer.thickness;
              }

              return acc + layer.thicknessAngled;
            },
            0,
          );
          const distanceFromSpacedArmor = firstLayer.point.distanceTo(
            lastLayer.point,
          );
          const finalDamage = Math.max(
            0,
            0.5 *
              shell.armor_damage *
              (1 - distanceFromSpacedArmor / shell.explosion_radius!) -
              1.1 *
                (lastLayer.thicknessAngled +
                  Math.min(penetration, totalSpacedArmorThickness)),
          );

          /**
           * Above is some peculiar math. We're multiplying 1.1 by the
           * thickness of the core plate plus the total spaced armor
           * thickness capped to the penetration itself. This is because
           * the shader is normalized by the penetration value; hence,
           * the total spaced armor thickness cannot ever be thicker
           * than the penetration. This is a precision error on the
           * shader-side and I do not intend on fixing it. Instead,
           * for parity's sake, I am capping the value here.
           */

          if (shot.in.layers.length > 1 || lastLayer.status === "blocked") {
            shot.in.status = finalDamage > 0 ? "splash" : "blocked";
            shot.damage = finalDamage;
          } else {
            shot.in.status = "penetration";
            shot.damage = shell.armor_damage;
          }
        } else {
          if (lastLayer.status === "blocked") {
            shot.in.status = "blocked";
            shot.damage = 0;
          } else if (lastLayer.status === "penetration") {
            shot.in.status = "penetration";
            shot.damage = shell.armor_damage;
          } else {
            const caster = new Raycaster();
            // https://math.stackexchange.com/a/13263/1222875
            const shellNormal = cameraNormal.clone().multiplyScalar(-1);
            const ricochetNormal = shellNormal
              .clone()
              .sub(
                lastLayer.surfaceNormal
                  .clone()
                  .multiplyScalar(2 * shellNormal.dot(lastLayer.surfaceNormal)),
              );

            caster.set(lastLayer.point, ricochetNormal);

            const ricochetIntersections = caster.intersectObjects(
              props.scene.children,
              true,
            );
            const outShot = shoot(
              lastLayer.point,
              ricochetIntersections,
              false,
              remainingPenetration,
              penetrationScale,
            );

            shot.in.status = "ricochet";
            if (outShot === null) {
              shot.damage = 0;
              shot.out = {
                surfaceNormal: ricochetNormal,
                layers: [],
                status: "ricochet",
              };
            } else {
              shot.damage = outShot.damage;
              shot.out = outShot.in;
              shot.out.surfaceNormal = ricochetNormal;
            }
          }
        }
      }

      shot.damage *= antagonistEqualizer.damage;

      const hasSpallLiner = Duel.state.protagonist.provisions.includes(
        SPALL_LINER_PROVISION_ID,
      );
      if (hasSpallLiner && shell.type === ShellType.SHELL_TYPE_HE) {
        shot.damage *= 1 + SPALL_LINER_HE_DAMAGE_DELTA;
      }

      return shot;
    },
    [camera],
  );

  return (
    <>
      {props.type === ArmorType.Primary &&
        jsxTree(node, {
          mesh(_, props, key) {
            return (
              <mesh
                {...props}
                key={`${key}-spaced-component`}
                renderOrder={0}
                material={omitMaterial}
                userData={
                  {
                    type: ArmorType.Primary,
                    thickness,
                  } satisfies ArmorUserData
                }
                onClick={(event) => {
                  event.stopPropagation();

                  const shot = shoot(event.point, event.intersections, true)!;

                  shot.penetrationChance = resolvePenetrationChance((scale) =>
                    shoot(
                      event.point,
                      event.intersections,
                      true,
                      undefined,
                      scale,
                    ),
                  );

                  Tankopedia.mutate((draft) => {
                    draft.shot = shot;
                  });
                }}
              />
            );
          },
        })}

      {props.type === ArmorType.Spaced && (
        <SpacedArmorSubSpaced node={node} thickness={thickness} />
      )}

      {props.type === ArmorType.External && (
        <SpacedArmorSubExternal
          node={node}
          thickness={thickness}
          variant={props.variant}
          clip={clip}
        />
      )}
    </>
  );
}